Taskforce Sweep

Taskforce Sweep was set up by Prime Minister Peter O'Neill in 2011 as one of his first acts.

He established a multi-agency investigation into the national planning department looking into long-running allegations that vast amounts of money earmarked for development projects largely disappeared without tangible results.

The Taskforce has since been expanded to other corruption investigations. In 2013, it began investigating allegations the country's finance department paid law firm Paul Paraka Lawyers more than $AU30 million without the proper approvals.

Sam Koim

In the wake of Paul Paraka's arrest, the head of Taskforce Sweep Sam Koim said his investigators had uncovered a racket of lawyers, politicians, bureaucrats, court officials, financial institutions and media organisations all colluding to pillage public coffers.

One of the key pieces of evidence in the inquiry was a letter, written in 2012, that appeared to be from Prime Minister Peter O'Neill authorising some of the payments to Paraka lawyers.

In January this year, Mr Koim said the letter did not appear to have legitimately come from Peter O'Neill's office, backing up Mr O'Neill's statement that it was a forgery.

But a "very confidential" letter from Mr Koim to PNG's police commissioner, leaked to media in June this year, outlines new evidence against Mr O'Neill.

"We have now received the Forensic Examination Report from the Sydney-based Forensic Document Services Pty Ltd confirming that the signature on the letter... directing payments to Paraka Lawyers is PM O'Neill's," Mr Koim said.

He said a subsequent letter added weight to the evidence.

"In that letter, PM O'Neill attempted to clarify his previous letter… and in doing so, confirms the existence of the first letter of 24 January 2012 which he openly denied," Mr Koim said.